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This paper presents a new way of organizing a wind farm with a large number of small to medium-sized turbines. Each wind generator has been included in a switching module of a modular multilevel converter (MMC), which generates the output voltage by near level control (NLC). The proposed topology reduces the number of semiconductors required, switching losses, and voltage filtering requirements. This topology replaces the usual configuration where each wind turbine is connected to a three-phase two-level back-to-back converter plus a filter and then connected in parallel with the other wind generators. To test the topology and its control performance, a case has been developed and simulated for generator configurations producing the same power, for generation imbalances between phases and for imbalances between arms. The analysis of the data shows that the converter works correctly and that it can deliver power to the grid in a balanced way even if the generation has imbalances. The generation imbalances between phases are compensated through the average value of the circulating current, while the imbalances between arms are compensated through the 50 Hz circulating current.
Fernando Martinez-Rodrigo; Dionisio Ramirez; Santiago de Pablo; Luis Herrero-De Lucas. Connection System for Small and Medium-Size Wind Generators through the Integration in an MMC and NLC Modulation. Energies 2021, 14, 2681 .
AMA StyleFernando Martinez-Rodrigo, Dionisio Ramirez, Santiago de Pablo, Luis Herrero-De Lucas. Connection System for Small and Medium-Size Wind Generators through the Integration in an MMC and NLC Modulation. Energies. 2021; 14 (9):2681.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Dionisio Ramirez; Santiago de Pablo; Luis Herrero-De Lucas. 2021. "Connection System for Small and Medium-Size Wind Generators through the Integration in an MMC and NLC Modulation." Energies 14, no. 9: 2681.
This article focuses on smoothing the large power peaks that wave energy converters (WECs) inject into the electrical grid. The study is carried out for a single WEC where the generated power is delivered to the grid by means of a power converter. Two different measures have been considered to improve the power quality of the grid connection. Firstly, the electronic converter has been chosen a modular multilevel converter (MMC) to allow replacing the standard high voltage capacitors of the DC link by low voltage ultracapacitors distributed across the modules of the MMC. Secondly, the MMC is controlled using a non-linear vector current control. The results show that the power delivered to the grid becomes approximately constant when using ultracapacitors. Furthermore, the non-linear vector current source provides the grid connection converter with the necessary fast dynamic response to avoid large variations in the DC voltage. Keywords: modular multilevel converter (MMC); non-linear vector current source; ultracapacitor; wave energy converter (WEC).
Fernando Martinez Rodrigo; Santiago De Pablo Gomez; Luis Carlos Herrero DE Lucas; Dionisio Ramirez Prieto. SMOOTHING OF THE INTERMITTENT POWER PROVIDED BY WAVE POWER PLANTS USING ULTRACAPACITORS AND A NON-LINEAR VECTOR CURRENT CONTROLLED MMC. DYNA 2021, 96, 61 -66.
AMA StyleFernando Martinez Rodrigo, Santiago De Pablo Gomez, Luis Carlos Herrero DE Lucas, Dionisio Ramirez Prieto. SMOOTHING OF THE INTERMITTENT POWER PROVIDED BY WAVE POWER PLANTS USING ULTRACAPACITORS AND A NON-LINEAR VECTOR CURRENT CONTROLLED MMC. DYNA. 2021; 96 (1):61-66.
Chicago/Turabian StyleFernando Martinez Rodrigo; Santiago De Pablo Gomez; Luis Carlos Herrero DE Lucas; Dionisio Ramirez Prieto. 2021. "SMOOTHING OF THE INTERMITTENT POWER PROVIDED BY WAVE POWER PLANTS USING ULTRACAPACITORS AND A NON-LINEAR VECTOR CURRENT CONTROLLED MMC." DYNA 96, no. 1: 61-66.
A new topology has been recently proposed for grid-connected photovoltaic (PV) systems, using modular multilevel converters (MMCs) and distributing PV panels throughout the MMC cells. This topology has two main advantages: it reduces the power losses related to moving the energy into the MMC capacitors from an external source, and it removes the losses and costs related to the DC to DC converters used to track the maximum power point on string converters or central converters, because that task is delegated to MMC cells. However, traditional pulse width modulation (PWM) techniques have many problems when dealing with this application: the distortion at the output increases to unacceptable values when MMC cells target different voltages. This paper proposes a new modulation technique for MMCs with different cell voltages, taking into account the measured cell voltages to generate switching sequences with more accurate timing. It also adapts the modulator sampling period to improve the transitions from level to level, an important issue to reduce the internal circulating currents. The proposed modulation has been validated using simulations that show a consistent behavior in the output distortion throughout a wide operation range, and it also reduces the circulating currents and cuts the conduction losses by half. The behavior of this new topology and this new modulation has been compared to the mainstream topology with external PV panels and also to a fixed carrier modulation.
Zaid A. Aljawary; Santiago De Pablo; Luis Carlos Herrero-De Lucas; Fernando Martinez-Rodrigo. Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction. Energies 2020, 13, 5585 .
AMA StyleZaid A. Aljawary, Santiago De Pablo, Luis Carlos Herrero-De Lucas, Fernando Martinez-Rodrigo. Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction. Energies. 2020; 13 (21):5585.
Chicago/Turabian StyleZaid A. Aljawary; Santiago De Pablo; Luis Carlos Herrero-De Lucas; Fernando Martinez-Rodrigo. 2020. "Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction." Energies 13, no. 21: 5585.
This paper is focused on the modular multilevel converter (MMC) topology that uses the near level control (NLC) method. Specifically, it addresses the relationship between the number of levels or switching modules, the switching frequency and the harmonics superimposed on the generated voltages and currents, making a comparison with the high and medium voltage AC codes. Furthermore, it also assesses the possibility of connecting the MMC to the electrical grid without using any coupling inductor, either using a transformer or simply directly. Finally, it shows how to automate the simulations necessary to select the number of levels and the switching frequency.
Fernando Martinez-Rodrigo; Luis C. Herrero-De Lucas; Santiago De Pablo; Alexis B. Rey-Boué; Dionisio Ramirez. Calculation of the number of modules and the switching frequency of a modular multilevel converter using near level control. Electric Power Systems Research 2018, 165, 68 -83.
AMA StyleFernando Martinez-Rodrigo, Luis C. Herrero-De Lucas, Santiago De Pablo, Alexis B. Rey-Boué, Dionisio Ramirez. Calculation of the number of modules and the switching frequency of a modular multilevel converter using near level control. Electric Power Systems Research. 2018; 165 ():68-83.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Luis C. Herrero-De Lucas; Santiago De Pablo; Alexis B. Rey-Boué; Dionisio Ramirez. 2018. "Calculation of the number of modules and the switching frequency of a modular multilevel converter using near level control." Electric Power Systems Research 165, no. : 68-83.
This paper is about the control of Modular multilevel converters, an innovative technology in the design of converters, which is beginning to be included in real installations. Papers about this topic include simulation models, circulating current reduction, voltage modulators, capacitor voltage balancing and control issues. The scheme for current source regulation used in this article includes all control loops, which are, from the outermost to innermost, DC bus voltage regulator, current regulator, voltage modulator, capacitor voltage balancing, and a PLL for the synchronization to the grid. Disposition-sinusoidal pulse width modulation is used as the voltage modulator, and an enhanced control strategy in the stationary reference frame for 3-phase MMCs is used for the inner current control loops. Very detailed simulations of the complete control system have been performed for both the enhanced control strategy in the stationary reference frame, and the well-known control in the synchronous reference frame, as well as some experiments using the hardware-in-the-loop simulation technique. The validation of these control strategies is made by a comparison of the capability of each one to compensate the harmonic distortions of the utility grid according to the grid code. The correct operation has been tested in the case of a strong/weak grid, unbalances and grid failures.
Alexis B. Rey-Boué; Fernando Martinez-Rodrigo; N.F. Guerrero-Rodríguez; Luis C. Herrero-De Lucas; Santiago De Pablo. Enhanced controller for grid-connected modular multilevel converters in distorted utility grids. Electric Power Systems Research 2018, 163, 310 -327.
AMA StyleAlexis B. Rey-Boué, Fernando Martinez-Rodrigo, N.F. Guerrero-Rodríguez, Luis C. Herrero-De Lucas, Santiago De Pablo. Enhanced controller for grid-connected modular multilevel converters in distorted utility grids. Electric Power Systems Research. 2018; 163 ():310-327.
Chicago/Turabian StyleAlexis B. Rey-Boué; Fernando Martinez-Rodrigo; N.F. Guerrero-Rodríguez; Luis C. Herrero-De Lucas; Santiago De Pablo. 2018. "Enhanced controller for grid-connected modular multilevel converters in distorted utility grids." Electric Power Systems Research 163, no. : 310-327.
This review article is mainly oriented to the control and applications of modular multilevel converters (MMC). The main topologies of the switching modules are presented, for normal operation and for the elimination of DC faults. Methods to keep the capacitor voltage balanced are included. The voltage and current modulators, that are the most internal loops of control, are detailed. Voltage control and current control schemes are included which regulate DC link voltage and reactive power. The cases of unbalanced and distorted networks are analyzed, and schemes are proposed so that MMC contribute to improve the quality of the grid in these situations. The main applications in high voltage direct current (HVDC) transmission along with other medium voltage (MV) and low voltage (LV) applications are included. Finally, the application to offshore wind farms is specifically analyzed.
Fernando Martinez-Rodrigo; Dionisio Ramirez; Alexis B. Rey-Boue; Santiago De Pablo; Luis Carlos Herrero de Lucas. Modular Multilevel Converters: Control and Applications. Energies 2017, 10, 1709 .
AMA StyleFernando Martinez-Rodrigo, Dionisio Ramirez, Alexis B. Rey-Boue, Santiago De Pablo, Luis Carlos Herrero de Lucas. Modular Multilevel Converters: Control and Applications. Energies. 2017; 10 (11):1709.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Dionisio Ramirez; Alexis B. Rey-Boue; Santiago De Pablo; Luis Carlos Herrero de Lucas. 2017. "Modular Multilevel Converters: Control and Applications." Energies 10, no. 11: 1709.
Dionisio Ramirez; Fernando Martinez-Rodrigo; Santiago de Pablo; Luis Carlos Herrero de Lucas. Assessment of a non linear current control technique applied to MMC-HVDC during grid disturbances. Renewable Energy 2017, 101, 945 -963.
AMA StyleDionisio Ramirez, Fernando Martinez-Rodrigo, Santiago de Pablo, Luis Carlos Herrero de Lucas. Assessment of a non linear current control technique applied to MMC-HVDC during grid disturbances. Renewable Energy. 2017; 101 ():945-963.
Chicago/Turabian StyleDionisio Ramirez; Fernando Martinez-Rodrigo; Santiago de Pablo; Luis Carlos Herrero de Lucas. 2017. "Assessment of a non linear current control technique applied to MMC-HVDC during grid disturbances." Renewable Energy 101, no. : 945-963.
This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results are analyzed by comparison to previous academic years and by satisfaction surveys. The new course design applies the jigsaw cooperative learning strategy to have students learn the theory of converters, solve problems, and perform simulations, before carrying out projects that solve real-world problems, such as the power converter for a competition solar vehicle (2014/15 course) and power converters for an air conditioner with inverter technology (2015/16 course). Rubrics were used to evaluate the students' work reports and the simulations. The project deliverables are presented and assessed in two design reviews, the first version covering the design and an open loop simulation, and the second covering the closed loop simulation and verification of specifications.
Fernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; Santiago de Pablo; Alexis B. Rey-Boué. Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters. IEEE Transactions on Education 2017, 60, 229 -237.
AMA StyleFernando Martinez-Rodrigo, Luis Carlos Herrero de Lucas, Santiago de Pablo, Alexis B. Rey-Boué. Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters. IEEE Transactions on Education. 2017; 60 (3):229-237.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; Santiago de Pablo; Alexis B. Rey-Boué. 2017. "Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters." IEEE Transactions on Education 60, no. 3: 229-237.
Fernando Martinez-Rodrigo; Santiago de Pablo; Luis Carlos Herrero de Lucas. Current control of a modular multilevel converter for HVDC applications. Renewable Energy 2015, 83, 318 -331.
AMA StyleFernando Martinez-Rodrigo, Santiago de Pablo, Luis Carlos Herrero de Lucas. Current control of a modular multilevel converter for HVDC applications. Renewable Energy. 2015; 83 ():318-331.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Santiago de Pablo; Luis Carlos Herrero de Lucas. 2015. "Current control of a modular multilevel converter for HVDC applications." Renewable Energy 83, no. : 318-331.
N.F. Guerrero-Rodriguez; Alexis B. Rey-Boué; Luis C. Herrero-De Lucas; Fernando Martinez-Rodrigo. Control and synchronization algorithms for a grid-connected photovoltaic system under harmonic distortions, frequency variations and unbalances. Renewable Energy 2015, 80, 380 -395.
AMA StyleN.F. Guerrero-Rodriguez, Alexis B. Rey-Boué, Luis C. Herrero-De Lucas, Fernando Martinez-Rodrigo. Control and synchronization algorithms for a grid-connected photovoltaic system under harmonic distortions, frequency variations and unbalances. Renewable Energy. 2015; 80 ():380-395.
Chicago/Turabian StyleN.F. Guerrero-Rodriguez; Alexis B. Rey-Boué; Luis C. Herrero-De Lucas; Fernando Martinez-Rodrigo. 2015. "Control and synchronization algorithms for a grid-connected photovoltaic system under harmonic distortions, frequency variations and unbalances." Renewable Energy 80, no. : 380-395.
N.F. Guerrero-Rodriguez; Luis Carlos Herrero de Lucas; S. De Pablo-Gómez; Alexis. B. Rey-Boué. Performance study of a synchronization algorithm for a 3-phase photovoltaic grid-connected system under harmonic distortions and unbalances. Electric Power Systems Research 2014, 116, 252 -265.
AMA StyleN.F. Guerrero-Rodriguez, Luis Carlos Herrero de Lucas, S. De Pablo-Gómez, Alexis. B. Rey-Boué. Performance study of a synchronization algorithm for a 3-phase photovoltaic grid-connected system under harmonic distortions and unbalances. Electric Power Systems Research. 2014; 116 ():252-265.
Chicago/Turabian StyleN.F. Guerrero-Rodriguez; Luis Carlos Herrero de Lucas; S. De Pablo-Gómez; Alexis. B. Rey-Boué. 2014. "Performance study of a synchronization algorithm for a 3-phase photovoltaic grid-connected system under harmonic distortions and unbalances." Electric Power Systems Research 116, no. : 252-265.
This paper analyzes the efficiency of three small commercial wind turbines, from different manufacturers and with different technology. Their actual energy production is compared with the case where they use turbine speed control to follow the wind speed variations. The simulation uses a Weibull probability distribution for the wind speed. A fixed pitch turbine with permanent magnets generator is simulated to demonstrate the wind turbine efficiency reduction when the speed is not controlled.
Fernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; Santiago De Pablo Gomez; J.M. Gonzalez De La Fuente. Analysis of the Efficiency Improvement in Small Wind Turbines when Speed Is Controlled. 2007 IEEE International Symposium on Industrial Electronics 2007, 437 -442.
AMA StyleFernando Martinez-Rodrigo, Luis Carlos Herrero de Lucas, Santiago De Pablo Gomez, J.M. Gonzalez De La Fuente. Analysis of the Efficiency Improvement in Small Wind Turbines when Speed Is Controlled. 2007 IEEE International Symposium on Industrial Electronics. 2007; ():437-442.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; Santiago De Pablo Gomez; J.M. Gonzalez De La Fuente. 2007. "Analysis of the Efficiency Improvement in Small Wind Turbines when Speed Is Controlled." 2007 IEEE International Symposium on Industrial Electronics , no. : 437-442.
This paper proposes a novel control system for fixed pitch wind turbine using an induction machine. It can obtain the maximum wind power for each wind speed without a wind speed sensor. The system measures the power generated by the turbine and changes the generator speed to increase the generated power. The induction generator is voltage source controlled. The good system performance is tested using simulation models and variable speed wind profiles.
Fernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; J. M Ruiz González; J. A Domínguez Vázquez. Wind Turbine with Induction Generator Controlled to Extract the Maximum Power. 2007 IEEE International Symposium on Industrial Electronics 2007, 443 -448.
AMA StyleFernando Martinez-Rodrigo, Luis Carlos Herrero de Lucas, J. M Ruiz González, J. A Domínguez Vázquez. Wind Turbine with Induction Generator Controlled to Extract the Maximum Power. 2007 IEEE International Symposium on Industrial Electronics. 2007; ():443-448.
Chicago/Turabian StyleFernando Martinez-Rodrigo; Luis Carlos Herrero de Lucas; J. M Ruiz González; J. A Domínguez Vázquez. 2007. "Wind Turbine with Induction Generator Controlled to Extract the Maximum Power." 2007 IEEE International Symposium on Industrial Electronics , no. : 443-448.
This communication deals with the study and the control of a squirrel cage induction generator intended to produce electrical energy in an autonomous or grid connected small wind generator. Small turbines use a permanent magnet synchronous machine without any system to produce the peak power for every wind speed. This paper proposes two generator control algorithms to track the peak power without wind and machine speed sensors. The application field are small wind power generators, which do not use this kind of sensors to reduce the cost. The system uses rotor flux oriented control of the induction machine. The first peak power control algorithm measures generated power and increases or decreases the torque reference to track the peak power. The second algorithm measures generated power too, but it modifies the speed reference to track the peak power. Simulation plots are included to prove the excellent performance with constant and variable wind power.
Fernando Martinez-Rodrigo; J.M. Ruiz Gonzalez; J.A. Dominguez Vazquez; Luis Carlos Herrero de Lucas. Sensorless control of a squirrel cage induction generator to track the peak power in a wind turbine. IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02 2003, 1 .
AMA StyleFernando Martinez-Rodrigo, J.M. Ruiz Gonzalez, J.A. Dominguez Vazquez, Luis Carlos Herrero de Lucas. Sensorless control of a squirrel cage induction generator to track the peak power in a wind turbine. IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02. 2003; ():1.
Chicago/Turabian StyleFernando Martinez-Rodrigo; J.M. Ruiz Gonzalez; J.A. Dominguez Vazquez; Luis Carlos Herrero de Lucas. 2003. "Sensorless control of a squirrel cage induction generator to track the peak power in a wind turbine." IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02 , no. : 1.